Pool Opening Levels


Well-known member
Sep 18, 2012
IL, NW of Chicago
I finally opened my pool last weekend. It was late due to several cold snaps, then an extended vacation. I was pleasantly surprised that the water wasn't even cloudy even though the water temperature was about 70F. I still had FC=1.5 after adding ~30-40% new water.

Anyway, my initial levels were:
Haven't tested CYA yet, but was ~30 last year before partial drain and refill, so I'm assuming ~20.

I added a box of Borax and got PH=7.6.
I added 13 cups of 12.5% bleach. That should have put FC~17.5. I think I miscalculated, because I wanted FC~10 assuming CYA=20.

By the end of the day
FC=4.5 (this seemed like a huge drop)

I passed the overnight test (no FC drop). I'll test at lunch today to see if an excessive amount of FC is being burnt off by the sun. I know I need to test CYA accurately and add stabilizer. I'll target CYA~40.

What I don't know is if I should tackle my high TA. It was also this high last year, and I just ignored it. I think it has some relationship with PH, but don't know why I should care about TA in and of itself. If I do want to lower it, pool math says to lower PH to 7.0 and aerate to get PH back. Any estimates on how long aeration takes by simply pointing an outlet upward? I don't really want to run with low PH for too long with my heater.


TFP Expert
Feb 3, 2014
Central Minnesota
Tackle the CYA first. That will help you hold FC during the day.

Don't worry about the TA unless you're seeing rapid pH rise. If you maintain your pH using muriatic acid, each time you add acid, the TA will go down. Eventually your pH rise will slow. If you're having quick pH rise, check out this article to deal with the TA more aggressively: Pool School - Lower Total Alkalinity If you're worried about your heater, only lower pH to 7.2 when actively lowering TA.


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
If you find your pH rising repeatedly and quickly, you can drop your TA some and it will help stabilize the pH. The way to drop your TA is to bring your pH down to 7.0-7.2 and then use aeration to raise the pH again....and again... It can take a few times but each time you drop your pH it drags the TA down with it. The aeration only affects the pH to make it rise again.

Since you have a heater I would NOT go lower than 7.2 and devise a method to aggressively raise the pH again. How about using a sump pump and directing the return hose above the water. You want to get as much "splash" as possible. Or use a simple fountain such as Skippy's fountain found in my signature line.


Well-known member
Sep 18, 2012
IL, NW of Chicago
Well, the strange thing is that I tend to have a PH that lowers over time (at least from last season). I have to keep adding Borax to keep it inline. From what others have told me, that makes no sense. I don't know what to do with the disconnect from expectation and my measurements.